Distillation of fermented mash has been practiced for ages. From the ancient Greeks and Romans, to the moonshiners of Appalachia, creative people have invented many different techniques for distillation. Distillation is a process of separating substances in a liquid mixture by selective evaporation and condensation. For fermented mash distillation, the goal may be to produce a liquid with high alcohol content.
Distillation techniques can also be used to extract essential oils from substances. For example, flavorings and other volatile elements may be extracted from virtually any plant product, such as hops, fruits, herbs, and many others. The extraction techniques may evaporate a solvent that may permeate the material, then produce “essential” oils. Such essential oils are “essential” in the sense that they contain the “essence of” a plant's fragrance or other characteristics.